Actuating device

ABSTRACT

A device for actuating a pair of spaced limit switches in which an actuating member is reciprocably mounted for movement between the limit switches. The device comprises a rotatably mounted shaft having a wire wound around a selected length of the shaft and defining a helical path. The opposite ends of the wire are fixed to the shafts in such a manner that when a portion of the actuating member is disposed in the helical path, that is, between any two adjacent turns of the wire, the adjacent sides of each of the remaining successive turns of the wire are normally in abutment. As the shaft is rotated in opposite directions, the wire reciprocally drives the actuating member between the limit switches.

United States Patent [1 1 Dalton 1 Feb. 6, 1973 541 ACTUATING DEVICE3,427,546 2/1969 Peartet al. ..338/180 [75] Inventor: Thomas B. Dalton,Muskegon, Primary Examiner Herman l Hohauser Attorney-Robert C. Hauke etal. [73] Assignee: Westram Corporation, Muskegon, I [57] ABSTRACT Mich.

[221 Filed: 24 1971 device for actuatinga pair of spaced limit switchesin which an actuating member 18 reciprocably [21] Appl. No.: 174,453mounted for movement between the limit switches.

The device comprises a rotatably mounted shaft hav- Related Apphcat'onData ing a wire wound around a selected length of the shaft [63]Continuation-in-part of Ser. No. 4,883, Jan. 22, definmg a hehcal path]The opposlte ends of the 1970, abandoned wire are fixed to the shafts msuch a manner that when a portion of the actuating member is disposed inthe 52 vs. C]. ..200/47, 74/458, 74/4247 Path that. W any adjacent "F.of the wlre, the ad acent sides of each of the remaining [51] Int. Cl.f..H0lh 3/lo Successive turns of the wire are normally in abutment [58]held 0 Search As the shaft is rotated in opposite directions, the wire200/47; 338/180 1 reciprocally drives the actuating member between thelimit switches. [56] References Cited UNITED STATES PATENTS Holmes..74/424.7

8 Claims, 8 Drawing Figures PATENIEDFEB 61973 3.715.530

Ill/Ill!!! INVENTOR.

THOMAS B. DALTON ACTUATING DEVICE CROSS REFERENCE TO RELATED APPLICATIONThe present application is a continuation-in-part of co-pending U. S.Pat. application Ser. No. 4,883, filed Jan. 22, 1970, now abandoned.

BACKGROUND OF THE INVENTION I. Field of the Invention The presentinvention relates to actuating devices and is particularly applicable tosuch devices having a rotating shaft which reciprocally drives anactuating member to alternately actuate a pair of spaced limit switches.

II. Background of the Invention Heretofore, such actuating devices havetaken the form of a pair of electrical limit switches which are adaptedto be actuated by means of an actuating member which is reciprocallymounted between the two switches. The actuating member usually comprisesa nut disposed intermediate the limit switches and adapted to travelaxially along a rotating threaded shaft. Although such limit switcheshave functioned in a satisfactory manner, theyare characterized bycertain disadvantages which the present invention overcomes. Thethreaded shaft of previous devices of course has a fixed number of turnsper inch with the number depending upon the desired application. Tomodify the control requires in many cases replacement of the shaft. Suchshafts are relatively expensive to manufacture as the grooves defined byeach successive turn of the threads must be relatively deep to insureproper retention of the actuating member. If control of the actuatingmember within close tolerances is required, the shaft must have agreater number of threads per inch and this increases the cost of themanufacture of such shafts.

Such shafts also must be completely replaced in the event of any damageduring operation and thus the cost of maintaining such devicesrepresents another disadvantage in their use.

It is therefore desirable to provide an actuating device of the typehereinbefore described in which the actuating member is driven by ashaft selectively rotated in opposite directions, but which is of asimple and inexpensive construction.

SUMMARY OF THE PRESENT INVENTION The present invention which will bedescribed subsequently in greater detail comprises a rotatable shafthaving a wire wound around a selected length of the shaft with adjacentsides of each successive turn of the wire being normally in abutment butbeing axially separable to define a helical path to receive an actuatingmember as the shaft is rotated to alternately engage and disengage apair of spaced limit switches. In the preferred embodiment, the wire issubstantially rectangular in cross section and has a radial depth whichsubstantially exceeds its axial thickness. The wire is wound around theshaft on its narrow edges such that the depth of the wire defines thedepth of the helical path. This not only insures that there will besufficient depth formed by the wire to securely retain the actuatingmember, but it also provides a device in which because of the relativelylarge number of turns per inch a quite accurate actuating device can beinexpensively achieved. Suitable clamping means releasably attach thewire to the shaft to permit it to be readily installed on any shaft andto permit it to be easily replaced in the event of damage to the wireduring use.

It is therefore an object of the present invention to provide animproved means for actuating limit switches which is extremely accurate,simple in construction and inexpensive to manufacture.

It is also an object of the present invention to provide an improvedmeans for actuating limit switches in which the driving portion thereofmay be easily and inexpensively replaced.

Other objects, advantages and applications of the present invention willbecome apparent to those skilled in the art when the accompanyingdescription of an example of the best mode contemplated for practicingthe invention is read.

BRIEF DESCRIPTION OF THE DRAWING The description herein makes referenceto the accompanying drawing wherein like reference numerals refer tolike parts and in which:

FIG. 1 is perspective view of an actuating device constructed inaccordance with the principles of the present invention;

FIG. 2 is a top plan view of the actuating device illustrated in FIG. 1;

FIG. 3 is a side elevational view of the actuating device illustrated inFIG. 1;

FIG. 4 is a transverse cross-sectional view of the actuating devicetaken along line 44 of FIG. 3;

FIG. 5 is a fragmentary perspective view of one example of the presentinvention prior to its installation on a shaft;

' FIG. 6 is a perspective view of the clamping means used in FIG. 1;

FIG. 7 is a fragmentary cross-sectional view taken along line 77 of FIG.4; and

FIG. 8 is a fragmentary perspective view of a modification of thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawing,there is illustrated an actuating device 10 of the rotary type havingmounted thereon a pair of conventional limit switches 12 and 14 adaptedto control an electrical device (not shown) when the limit switches 12and 14 are actuated by an actuating member 16 which, in turn, isreciprocally driven by a rotating shaft 18. The shaft 18 could, forinstance, be the output shaft of an electric motor and the actuatingdevice 10 and the limit switches 12 and 14 could be connected to theelectric motor so that after rotation of the shaft 18 for apredetermined number of revolutions in one direction one of the limitswitches would be engaged by the actuating member 16 to shut off theelectric motor or to reverse the direction of rotation of the shaft fora predetermined number of revolutions.

The limit switches l2 and are preferably attached to the upper surfaceof one leg .20 of a generally L- shaped member 22. The other leg 24 ofthe L-shaped member 22 has an aperture 26 (FIG. 1) through which shaft18 extends. Aperture 26 is sized to permit relative rotational movementbetween the shaft 18 and the leg 24. One end 28 of the shaft 18 extendsoutwardly from the device for connection to the rotary output of anelectrical device, such as the aforementioned electric motor (notshown), whose operation it is desired to control and is adapted torotate therewith, either directly or through suitable gearing means. Theopposite end 32 of shaft 18 is rotatably supported by a suitable bearing34 which, in turn, is fixedly mounted to the end of the leg by anysuitable means, such as by welding or the like.

A flat wire 36 is wound around the outer periphery of the shaft 18 for aportion of the length of the shaft 18 and, as can be seen in FIGS. 5 and7, the wire 36 is preferably rectangular in cross section having sides38 with a radial depth substantially exceeding the axial thickness ofthe peripheral edge 40 of the wire 36. The

wire 36 is wound around the shaft 18 on its edges 40 such that the sides38 of the wire 36 define the depth of the spacing between the successiveturns of the wire 36. As can be best seen in FIGS. 1, 3,4 and 7, theadjacent sides 38 of each successive turn of the wire 36 are normally inabutment, except for that portion engaged by a pair of flanges 42 and 44of a U-shaped bracket 46 carried by the actuating member 16. The spacingformed by the separation between turns of the wire 36 as the flanges 42and 44 move along the shaft 18 defines a helical path 48 along thelength of the shaft 18 and causes the actuating member 16 to be movedback and forth along the length of the shaft 18 as the shaft is rotatedin opposite directions. The number of revolu- 'tions of the shaft 18necessary to move the actuating member 16 any desired distance along theshaft 18 will depend .upon the number of turns of wire per inch on theshaft 18 and the total length of the wire 36. Thus, it can be seen thatany selected control of the actuating member 16 may be obtained by usingwires having various thicknesses of the edge 40 and various lengths soas to accommodate the particular application in which the limitswitches-are to be utilized.

The opposite ends of the wire 36 are attached to the shaft 18 by meansof a pair ofclamps 52 and 54 (FIG.

propriate pair of adjacent turns of thewire 36 and the clamps 52 and 54are so positioned on the shaft 18 that the remaining adjacent sides 38of each adjacent turn of the wire 36 are in abutment. The screws 55 arethen tightened to securely mount the clamps 52, 54 and the wire 36 totheshaft 18. Since the clamps 52 and 54 and the wire 36 rotate with theshaft 18, the flanges 42 and 44 and thus the actuating member- 16 willbe reciprocally driven longitudinally along the shaft 18. As the shaft18 is rotated, each adjacent side 38 of each successive turn of the wire36 will be momentarily axially separated by the flanges 42 and 44 as thesame follow the helical path 48. In order to achieve this separation,each successive turn ofthe wire 36 moves axially a distance equal to thewidth of each flange 42 and 44.

The clamps 52 and 54 permit easy removal and replacement of the wire 36in the event it fails during use or if a different control is desired.The wire 36 is preferably made from a spring steel, however, othermaterials having specific desired characteristics, such as wear orcorrosion resistant materials, may be used depending upon the particularapplication.

The limit switches 12 and 14, respectively, have a pair of movablecontacts 56 and 58, each of which is adapted to make and/or break anelectrical circuit in their respective limit switches 12 and 14 togenerate an appropriate signal, which in turn controls the electricaldevice. The movable contacts 56 and 58 are positioned with respect tothe upper surface of the leg 20 in such a manner that they extend overan elongated slot 60 in the leg 20. The slot 60 is disposed along anaxis parallel to the longitudinal axis of the shaft 18 and functions toguide the movement of the actuating member 16 in a manner to bedescribed hereafter.

The actuating member 16 is comprised of three components: an invertedT-shaped member 62, a rectangularly shaped member 63 carried at the topof the T- shaped member 62, and the U-shaped bracket member 46, all ofwhich are coupled to each other by threaded screws 65. The upper leg ofthe member 62 extends through the slot 60 and is guided thereby as theactuating member 16 travels between the movable contacts 56 and 58. Eachflange 42 and 44 of the U-shaped member 46 has a semi-circular portion,one of which is shown at 66 in FIG. 4. The semi-circular portions 66 oneach flange 42 and 44 are adapted to extend into, at axially spacedpoints, the helical path 48 defined by the axially separated sides 38 ofthe wire 36 and are moved axially by the wire 36 as the shaft 18 turnsin the same manner as a nut would move along a rotating threaded screw.As the shaft 18 is rotated in a clockwise direction as viewed in FIG. 4,the actuating member 16 will be driven by the wound wire 36 towards themovable contact 56, that is, to the left as viewed in FIG. 3. As theshaft 18 is rotated in the opposite direction, that is, counterclockwiseas viewed in FIG. 4, the actuating member 16 will be moved toward themovable contact 58, that is, to the right as viewed in FIG. 3.

Thus, the wound spring wire 36 provides a helical path similar to thespiral groove on the threaded shafts of the previously described devicesand functions in a similar manner to drive the actuating member 16 ineither direction between the pair of spaced limit switches 12 and 14 toalternately engage and actuate the limit switches.

In order to insure a smooth engagement of the actuating member 16 witheach of the movable contacts 56 and 58, the opposite ends of therectangularly shaped member 63 are beveled to form cam surfaces 70 and72 (FIG. 2), which respectively engage the movable contacts 56 and 58 todisplace the same. The limit switches 12 and 14 operate in a mannerwhich is well known in the art and are adapted to complete an electriccircuit when their associated movable contacts 56 and 58 are engaged bythe actuating member 16 to generate an electrical signal which activatesother electrical circuitry, also known in the art, to, for example,reverse the direction of rotation of the particular electrical device tobe controlled, such as an electric motor.

Referring to FIG. 8, there is illustrated a modified actuating member 74having an L-shaped member 77 attached to the top of the leg of theT-shaped member 62 by the screw 65. By providing members 77 of variouslengths, the amount of travel of the actuating member 16 between thelimit switches 12 and 14 can be varied to suit any desired application.

In either embodiment of the invention, if the shaft 18 is the outputshaft of an electric motor, for instance, the actuating device can beused to control the direction and number of revolutions of such anoutput shaft. After the electric motor has been energized to rotate theshaft 18 a predetermined number of revolutions, the appropriate limitswitch will be engaged by either member 63 or the member 77 to reversethe direction of the electric motor. The shaft 18 will then be rotatedin a reverse direction until the opposite limit switch is engaged byeither the member 63 or the member 77, whereupon the direction ofrotation of the electric motor is again reversed.

The present invention has particular application to electric motors inthat a limit switch assembly can be provided for such devices by simplyclamping the assembly of the present invention to the output shaft ofthe motor. Heretofore it would have been necessary to undertakeexpensive modifications of the output shaft or to provide another shaftcoupled to the output shaft to provide a limit switch assembly forelectric motors.

Having thus described the invention, what is claimed is as follows:

1.An actuating device comprising:

an actuating member mounted for movement toward at least one contactpoint;

a rotatably mounted shaft having at least one continuous helical pathcircumscribing said shaft along a selected length thereof, a portion ofsaid actuating member extending into said helical path and movable alongsaid selected length in response to the rotational movement of saidshaft;

said helical path comprising spaces between successive turns of a wirewound around said shaft, the adjacent sides of each turn of said wirenormally being abutment and being axially separable to accommodate saidactuating member portion as said actuating member moves along saidselected length.

2. The actuating device defined in claim 1 and in which said wire isrectangular in cross section and has a pair of edges of a smallerdimension than another pair of said edges, said wire being wound aboutsaid shaft on one of its shorter edges so that the longer edges definethe depth of said helical path, the adjacent longer edges of said wirenormally being in abutment.

3. The actuating device as defined in claim 1 includhaving a slottedportion generally parallel to the axis of rotation of said shaft, saidactuating member being mounted in said slotted portion, said switchesbeing mounted on said base proximate one end of said slotted portion andadapted to be engaged by said actuating member as the same is drivenalong said slotted portion by said rotating shaft.

7. The actuating device as defined in claim 6 wherein said wire has aradial width which substantially exceeds its axial thickness, said wirebeing wound around said shaft on one of its edges such that the radialwidth of said wire defines the depth of said helical path.

8. The actuating device as defined in claim 7 including means forreleasably attaching said wire to said shaft.

1. An actuating device comprising: an actuating member mounted formovement toward at least one contact point; a rotatably mounted shafthaving at least one continuous helical path circumscribing said shaftalong a selected length thereof, a portion of said actuating memberextending into said helical path and movable along said selected lengthin response to the rotational movement of said shaft; said helical pathcomprising spaces between successive turns of a wire wound around saidshaft, the adjacent sides of each turn of said wire normally beingabutment and being axially separable to accommodate said actuatingmember portion as said actuating member moves along said selectedlength.
 1. An actuating device comprising: an actuating member mountedfor movement toward at least one contact point; a rotatably mountedshaft having at least one continuous helical path circumscribing saidshaft along a selected length thereof, a portion of said actuatingmember extending into said helical path and movable along said selectedlength in response to the rotational movement of said shaft; saidhelical path comprising spaces between successive turns of a wire woundaround said shaft, the adjacent sides of each turn of said wire normallybeing abutment and being axially separable to accommodate said actuatingmember portion as said actuating member moves along said selectedlength.
 2. The actuating device defined in claim 1 and in which saidwire is rectangular in cross section and has a pair of edges of asmaller dimension than another pair of said edges, said wire being woundabout said shaft on one of its shorter edges so that the longer edgesdefine the depth of said helical path, the adjacent longer edges of saidwire normally being in abutment.
 3. The actuating device as defined inclaim 1 including means for releasably attaching said wire to saidshaft.
 4. The actuating device as defined in claim 3 wherein saidreleasably attaching means comprises a pair of clamps attaching theopposite ends of said wire to said shaft.
 5. The actuating device ofclaim 1 including at least one switch disposed in the path of saidactuating member.
 6. The actuating device as defined in claim 5including a mounting bracket having a base and at least one flangeextending at right angles thereto, said bracket being mounted to saidshaft by said flange, said base having a slotted portion generallyparallel to the axis of rotation of said shaft, said actuating memberbeing mounted in said slotted portion, said switches being mounted onsaid base proximate one end of said slotted portion and adapted to beengaged by said actuating member as the same is driven along saidslotted portion by said rotating shaft.
 7. The actuating device asdefined in claim 6 wherein said wire has a radial width whichsubstantially exceeds its axial thickness, said wire being wound aroundsaid shaft on one of its edges such that the radial width of said wiredefines the depth of said helical path.